Plasma samples were not specifically tested in-house with this assay but there is no reason to believe it would not work just fine. It is recommended that you test for linearity to find the optimal dilution. Also, looking through the literature, there are a few research articles where this kit was used to determine the levels of DNA damage in plasma (Luloff et al., 2011; Mayer et al., 2011). You might be able to gather further information regarding plasma samples handling from there.